For heart attack, prevention strategies seem to work

A large scale study of Kaiser Permanente health policy holders in Northern California shows that hospital admissions for heart attack dropped significantly between 1999 and 2008 — coinciding with the implementation of public health efforts such as smoking bans, lowered target levels for blood pressure and cholesterol and more widespread use of preventive medications such as statins, beta blockers and aspirin regimes. In the study, published in the New England Journal of Medicine, researchers analyzed more 46,000 hospitalizations for myocardial infarction between 1999 and 2008. They conclude that, likely due to more widespread adoption of preventive measures, hospital admissions due to heart attack dropped by 24% during the period studied.

While previous research has analyzed the impact of preventive strategies at reducing risk factors for heart attack, this latest study, led by cardiologist Dr. Robert Yeh of Harvard Medical School and Massachusetts General Hospital, set out to examine how preventive techniques affected actual incidence of heart attacks. They found that the occurrence of heart attack jumped slightly from 274 per 100,000 person-years (a measurement that indicates the duration of follow-up for the study population) in 1999 to 287 per 100,000 person-years in 2000. Yet, after that, the prevalence of heart attack dipped dramatically — to 208 per 100,000 person-years by 2008.

During the period studied, not only to health care providers lower target levels for blood pressure and cholesterol, but they also improved patient adherence to these goals. (While only 40% of patients were meeting target blood pressure levels in 1999, for example, by 2008, 80% of patients were.) The authors also point out that the findings are particularly significant because they indicate that prevention strategies may be effective even in spite of the concurrent impact of cardiovascular risk factors such as obesity and diabetes.

The dramatic improvement — a 24% reduction in heart attacks in the span of 8 years — suggests that preventive techniques may actually be, at least in part, effectively helping to prevent heart attacks. As they sum up:

“The lower incidence of myocardial infarction … is probably explained, at least in part, by substantial improvements in primary-prevention efforts.”

A study released today in the U.K. suggests that preventive efforts may be reducing heart attack incidence among British citizens as well. In the analysis of all hospital admissions between 2002 and 2009, researchers found that, after the national smoking ban went into effect in July 2007, hospitalization for heart attack dropped by 2.4% in the following year and a half, the BBC reports. The researchers estimate that the modest improvement may have saved the U.K.’s National Health Service some $11.5 million (£8 million) in medical costs.

Yet amid the promising news about the impact of preventive strategies, in an editorial accompanying the Kaiser Permanente study, Jeremiah Brown and Gerald O’Connor of the Dartmouth Institute for Health Policy and Clinical Practice point to some sobering statistics about the extraordinarily lopsided nature of heart disease prevalence across the U.S.

Figure 1 Rates of Death Due to Heart Disease among Adults 35 Years of Age or Older, 2000–2006, by County. Image courtesy of the New England Journal of Medicine, 2010.

While public health strategies such as smoking bans have had a significant impact on heart disease related deaths — the authors point out that heart-disease related mortality has dropped 22% among men and 23% among women in the past decade — people from particular regions of the country, such as lower Mississippi and Oklahoma, continue to face as much as double the risk of death due to heart disease compared with those living in other parts of the U.S. While the Kaiser Permanente study found that preventive efforts met success in spite of worsening public health issues such as diabetes and obesity, Brown and Connor point out that the prevalence of certain risk factors varies dramatically by socioeconomic status — and in turn by geography.

For example, among individuals living below the poverty line, they point out, there is a consistently higher prevalence of heart disease risk factors such as high cholesterol, obesity, and routine physical activity has actually decreased — even as it has increased among wealthier members of the population. Truly effective prevention strategies need to work to close these gaps, the authors argue.